Like you mention I'm far less concerned about fabbing it up on the road king and have four more curiosity about if it will work or what it will take to make it work on the Road Glide. Good to see that someone else has already played with the idea some. What swivel did you use? I'm looking forward to all the parts getting here hopefully end of next week so can begin to play with it some.
Used two of these ball mounts, one on each end: RAM 2" x 1.7" Base with 1" Ball that Contains the Universal AMPs Hole Pattern for the Garmin zumo, TomTom Rider & Urban Rider,
http://www.rammount.com/part/RAM-B-347Uand one of these swivel arms: RAM Short Double Socket Arm for B Size 1" Balls
http://www.rammount.com/part/RAM-B-201U-AThey also make a medium length and a long-length RAM Double Socket Arm for B Size 1" Balls, part #s RAM-B-201U and RAM-B-201U-C if you want the GPS closer to you, although it's more stress on the w/s with that lever arm.
I'm wondering how it might fit on an '09 SERG?
One like this might be better for the RG w/s angle: RAM Double Socket Swivel Arm for 1" Balls (Overall Length: 6.25")
http://www.rammount.com/part/RAP-B-200-2U